Positioning functions can provide a user with various services, e.g., working, entertainment, daily life, etc. Typical location services include assistance services, e.g., an emergent medical service, an emergent location service, etc.; location-based information services, e.g., a search for information about proximate restaurants and entertainment sites, an inquiry throughout a yellow page, etc.; and advertisement services, e.g., promotion and discount information; and also location-based billing, tracking or other services.
In a positioning as per a cell_ID (the ID stands for an identifier) method, which is a method of positioning based upon cell coverage, the location of a target UE is estimated from known geographical information about a serving cell, where the information about the serving cell can be obtained through calling, paging, Tracking Area (TA) updating or otherwise.
In a method of positioning as per a Timing Advance (TA) and an Angle of Arrival (AoA), a timing advance, an angle of arrival and other factors have been taken into account in addition to the method of positioning as per a cell_ID for the purpose of more precise positioning.
An evolved Node B (eNB) obtains the AoA of a signal transmitted by a User Equipment (UE) over an intelligent antenna, where the UE is located on a radial line which starts at the eNB and which is rotated clockwise from the exact north by an angle which is the AoA; and
The TA can be calculated as the difference, reported by the UE, between the time when the signal is received and the time when the signal is transmitted by the UE, plus the difference, measured by the eNB, between the time when the signal is received and the time when the signal is transmitted (the TA calculated this way is referred to as a TA Type 1), or can be measured by the eNB in a dedicated random access procedure (the TA calculated this way is referred to as a TA Type 2). The TA is multiplied by the velocity of light divided by two represents the distance between the UE and the eNB, where the UE is located on a circle centered at the eNB and with the distance between the UE and the eNB as a radius. Furthermore position information about the UE can be derived from angle information of the AOA. As illustrated in FIG. 1:
The method of positioning as per a TA plus an AoA is typically applicable only to network-based positioning primarily for the reason that the AoA can only be measured by the eNB and the TA Type 1 and the TA Type 2 are also calculated or measured by the eNB, that is, all the measured quantities involved in this method of positioning are provided by the eNB. All of these measured quantities can be provided by the eNB to a location server, so the support of network-based positioning can accommodate the purpose of positioning. Thus an accompanying advantage of this method lies in that a UE for which no location service is supported can also be positioned in this method.
However with the existing methods of positioning, the difference in altitude between the UE and the eNB may not be available, thus resulting in a significant error in a result of positioning.